Billet-guiding system for a continuous casting plant

ABSTRACT

In a strand guide for a continuous casting plant comprising a plurality of strand supporting elements for supporting the strand, in particular support segments carrying supporting rollers, several support segments being fastened adjacent each other on a supporting framework designed in one piece in its longitudinal extension, each support segment is fastened to the supporting framework by a fixed bearing and a movable bearing spaced apart therefrom in the longitudinal extension of the strand guide, each support segment, by at least one bearing, is pivotally mounted to the supporting framework so as to be pivotable about an axis, the axis being oriented transversely with respect to the longitudinal extension of the strand guide and horizontally, as well as in a vertical plain passing through the longitudinal extension of the supporting framework and by at least one bearing is mounted so as to be adjustable with respect to the supporting framework in a direction toward the pivoting movement of the support segment. For simple adjustment of the correct position of the support segments, a measuring device for detecting the pivoting movement of the support segment, preferably a position sensor or an angle measuring device, is provided which, via a controller, is coupled with an adjusting device for adjusting the position of the support segment.

BACKGROUND OF THE INVENTION

The invention relates to a strand guide for a continuous casting plant,in particular for a continuous casting plant for steel, comprising aplurality of strand supporting elements for supporting the strand, inparticular support segments carrying supporting rollers, several supportsegments being fastened adjacent each other on an optionally arcuatesupporting framework designed in one piece in its longitudinalextension, wherein each support segment is fastened to the supportingframework by means of a fixed bearing and a movable bearing spaced aparttherefrom in the longitudinal extension of the strand guide and eachsupport segment by at least one bearing (fixed and/or movable bearing)is pivotally mounted to the supporting framework so as to be pivotableabout an axis, said axis being oriented transversely with respect to thelongitudinal extension of the strand guide and horizontally, as well asin a vertical plane passing through the longitudinal extension of thesupporting framework and by at least one bearing (fixed and/or movablebearing) is mounted so as to be adjustable with respect to thesupporting framework in a direction roughly perpendicular to thelongitudinal extension of the supporting framework to enable thepivoting movement of the support segment, and a method of adjusting theposition of support segments.

A strand guide of this kind is known e.g. from DE-A - 30 29 991. There,alignment of the support segments is feasible by displacing the supportmeans at the bearings, namely through manipulations which have to beeffected manually. However, this involves complications since itrequires the plant to be out of operation and moreover can only becarried out in cooled-down condition. Hence, deformation caused bythermal expansion and influences occurring after start-up cannot betaken into account.

From EP-B - 0 222 732 a strand guide is known in which several supportsegments each carrying a plurality of strand guide rollers are arrangedon a continuous longitudinal carrier designed in one piece, with thesupport segments being mounted on the longitudinal carriers via carryingbrackets rigidly fastened to the longitudinal carriers by means offitting pins, two neighboring support segments each being commonlymounted on the carrying brackets by means of carrying elements arrangedon their ends. Each carrying bracket has a recess immovably receivingthe carrying element of a support segment and a recess receiving thecarrying element of the neighboring support segment with a play, therebyforming movable and fixed bearings. The play extends parallel to thepath of the strand guide so that a thermal expansion of the supportsegments or of the longitudinal carrier will have no adverse effect onthe accuracy of the strand guide.

From FR-A - 2 447 764 a strand guide is known in which strand guide thecarrying brackets are pivotally fastened to the single-piecelongitudinal carrier so that by pivoting the carrying brackets a supportsegment supported on the carrying bracket is lifted or lowered on theone hand and the neighboring support segment supported on the samecarrying bracket is moved in a direction counter to the first one. Inthis way, the neighboring support segments can be aligned while avoidinga step-like transition in the path of the strand guide. One disadvantageinvolved here is that at least two neighboring support segments arepivoted in each instance if there is a height step at a site oftransition from one support segment to the other support segment. Thisrenders it difficult to keep to the path of the strand guide whilemaintaining the deviation from the ideal path of the strand guide asslight as possible, i.e. for instance to observe a circular-arc-shapedpath of the strand guide, in the case of an arcuate strand guide. Majordeviations of several support segments from the ideal position may occursince none of the support segments is fastened to the supportingframework by means of a fixed bearing.

The invention aims at avoiding these disadvantages and difficulties andhas as its object to further develop a strand guide of the initiallydescribed kind in such a way as to ensure precise adjustment of thesupport segments during the entire operating time of the strand guide,requiring only short interruptions, if any, for adjusting the strandguide.

SUMMARY OF THE INVENTION

According to the invention, this object is achieved in that a measuringdevice for detecting the pivoting movement of the support segment,preferably a position sensor or an angle measuring device, is providedwhich via a controller is coupled with an adjusting device for adjustingthe position of the support segment.

A particularly simple and robust construction of a strand guide ischaracterized in that vertically adjustable shims are provided foradjusting the position of the adjustable bearing.

For adjusting the adjustable bearing, there preferably is provided athreaded spindle, or according to another embodiment an axiallydisplaceable wedge which is movable by means of a hydraulic adjustingcylinder, or according to yet another embodiment a hydraulic adjustingcylinder which acts between the supporting framework and the supportsegment.

A preferred embodiment is characterized in that for actuating thehydraulic adjusting cylinder there is provided at least one directionalcontrol valve which is capable of being switched via a three-levelcontroller or a higher-level controller or a controller with apulse-width output to which the actual value detected by the positionsensor can be fed via a coupling.

The provision of a directional control valve enables a very simplecontrol technique. A particularly high accuracy, which could be achievede.g. by using the servo valve technology, is renounced here, yet inaccordance with the invention there result the advantages ofsubstantially reduced costs and a substantially reduced sensitivity todisturbances such as e.g. contamination of the oil or pressure drops orthe like as compared to the servo valve technology. Surprisingly, thedirectional control valve technology has proved satisfactory forcontinuous casting operations even in the case of sensitive steelgrades.

By employing a controller with a pulse-width output, nearly continuouscontrol as it is typically achieved using servo or proportional valvescan be achieved even with directional control valves. In the case of theon-off valve, the variable valve opening which is used with thesecontinuously operating valves is replaced with a sequence of pulsedvalve openings. This enables positioning operations to be carried outwith high precision.

The servo valve technology enables very sensitive and rapid control ofhigh outputs by means of small control inputs due to the supportingeffect of the medium that flows through. The servo valve technology ismainly applied for difficult positioning tasks in machine tooltechnology. The demands both in terms of material and cost for realizingthe servo valve technology are correspondingly high. Maintenance andmeasures for avoiding disturbing influences are likewise expensive.

Application of the servo valve technology in connection with continuouscasting technology is known from U.S. Pat. No. 3,812,900; it allowsadjusting the position of the movable strand guide roller with utmostprecision. Disadvantages of this method are the great expenditures interms of materials which are incurred in applying the servo valvetechnology as well as the great sensitivity to a contamination of thesame; difficulties may result in heavy-duty iron- and steelworksoperations.

Since according to the invention only minor volume flows are requiredfor adjusting a support segment whereas the total system operates athigh pressures (e.g. 160 bar), a throttle or screen suitably isintegrated in at least one hydraulic working duct of the hydraulicadjusting cylinder leading from a pressure-medium supply station to thedirectional control valve or from this latter to the hydraulic adjustingcylinder.

A preferred embodiment is characterized in that a current control valvewith rectification is integrated in at least one hydraulic working ductleading from a pressure-medium supply station to the directional controlvalve or from this latter to the hydraulic adjusting cylinder.

The provision of a current control valve leads to an adjusting velocitywhich is almost independent of the load and the corresponding hydraulicpressures. By tuning the design of the 3- or 5-level controller to thisadjustment speed and the response and fall time of the respectivedirectional control valve it becomes feasible to reach the desiredsetpoint for all types of loading in a very precise and direct manner.

Another preferred embodiment is characterized in that in the hydraulicworking duct leading to and/or away from the hydraulic adjustingcylinder there is provided a throttle or screen connected immediatelyupstream respectively downstream of the hydraulic adjusting cylinder.

In order to achieve different adjustment speeds of the piston over theadjustment course of the hydraulic adjusting cylinder and hence animproved accuracy, an additional directional control valve preferably isprovided connected in parallel with a throttle or screen or with thecurrent control valve with rectification, wherein a five-levelcontroller or a higher-level controller is suitably provided as acontroller.

The invention further relates to a strand guide which is characterizedin that the position sensor is formed by a balancing cylinder connectedin parallel with the hydraulic adjusting cylinder and actingdiametrically opposed to the hydraulic adjusting cylinder and which onthe one hand is connected with the supporting framework and on the otherhand with a support segment.

A method of adjusting and/or correcting the position of support segmentsfastened successively in a supporting framework and provided with strandsupporting elements, in particular supporting rollers, with each supportsegment being fastened to the supporting framework by means of a fixedbearing and a movable bearing spaced apart therefrom in the longitudinalextension of the strand guide, is characterized in that of neighboringsupport segments whose strand supporting elements result in a path ofthe strand guide exhibiting a jump at the junction point of the supportsegments, the support segment adjoining the neighboring support segmentby its adjustable bearing is pivoted about its bearing permitting apivoting movement, namely is pivoted until the jump has been minimized.

In this method, preferably the support segment is pivoted until atangent circle laid to three neighboring strand supporting elements ofwhich one strand supporting element belongs to one support segment andtwo strand supporting elements to the neighboring support segmentexhibits a radius or a curvature whose deviation from the desired(ideal) radius or from the associated curvature becomes a minimum.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial lateral view of a strand guide of a of a continuouscasting plant.

FIGS. 2 and 3 are schematic sketches explaining the invention.

FIG. 4 illustrates the change in the curvature at the transition fromthe imprecise mounting of the segments by the correction to be carriedout according to the invention.

FIG. 5 illustrates a preferred controlling scheme according to theinvention for the hydraulic adjusting cylinder in schematicrepresentation.

FIG. 6 illustrates the arrangement thereof on a strand guide, also inschematic representation.

FIGS. 7 and 8 show the functioning of a three-level controller and afive-level controller in dependence on the deviation.

FIG. 9 illustrates a basic circuitry comprising a current control valve.

FIG. 10 illustrates the basic circuitry comprising a 4/3-portdirectional control valve with screens.

FIG. 11 shows a valve-throttle combination for realizing two adjustmentspeeds of the piston of a hydraulic adjusting cylinder.

DESCRIPTION OF PREFERRED EMBODIMENTS

A strand guide 1 of an arcuate continuous casting plant is provided withone-piece longitudinal carriers of arcuate design for receiving severalsupport segments 2, which carriers serve as a supporting framework 3 forthe support segments 2 and are each supported on the foundation by meansof bearings (not illustrated).

According to the overall length of the strand guide 1, two or severallongitudinal carriers 3 are provided successively in the longitudinaldirection of the strand guide, with each longitudinal carrier 3 carryingtwo or several support segments 2 in each case, strand supportingelements 4, in particular supporting rollers, being arranged on thesupport segments. If two or several longitudinal carriers 3 are arrangedsuccessively, one of the segments may be provided in order to bridge thelongitudinal carriers 3, i.e. it may be mounted both on the firstlongitudinal carrier 3 and on the subsequent longitudinal carrier 3.

Following the arcuate longitudinal carrier 3, the strand guide 1 extendsat least over the length throughout which the strand has a liquid core,so that, generally, longitudinal carriers 3 may also be arranged in thesame manner in the horizontal portion of the strand guide 1 locatedafter the arcuate portion of the strand guide 1 and each of them willlikewise carry two or several support segments 2. Instead of thelongitudinal carrier 3 there may also be provided cast concretefoundations or a single concrete foundation, on which the supportsegments 2 are mounted. Where a concrete foundation serves as thesupporting framework 3, the support segments 2 are suitably arranged onsteel plates fastened to said concrete foundation, with preferably nomore than two to four bearings being provided on said steel plates.

Each support segment 2 is formed by lower roll supports 5 and upper rollsupports 6 connected with each other by means of tension rods 7. Thetension rods extend roughly perpendicular with respect to thelongitudinal extension 8 of the strand guide 1 and hence also withrespect to the supporting framework 3 so that in the case of an arcuatestrand guide 1 they are directed roughly towards the center ofcurvature. At the upper ends of the tension rods 7, i.e. on their endslocated inside the arc, hydraulic adjusting cylinders 9 are provided bymeans of which it is feasible to alter the roller gap 10 of the rollers4 facing each other, which are rotatably fastened to the roll supports 5and 6. To accomplish this, the upper roll support 6 is moved relative tothe lower roll support 5 along the tension rods 7 by a predeterminedmeasure and is positioned after reaching the desired position.

Each of the support segments 2 by the lower roll support 5 is fastenedto the longitudinal carrier 3 at one end by means of a fixed bearing 11and at the opposing end by means of a movable bearing 12, with one fixedbearing 11 each of a support segment 2 being arranged subsequent to amovable bearing 12 of the neighboring support segment 2, resulting in analternate arrangement of movable and fixed bearings. The fixed bearings11 are designed such that the support segments 2 are capable of beingpivoted about a horizontal axis 13 extending parallel with respect tothe supporting rollers 4 and passing through the fixed bearings 11,namely are pivotable in a plane that is parallel to the vertical plane(=the plane of projection of FIGS. 1 to 3) extending in the longitudinalextension of the strand guide.

The movable bearings 12 enable this pivoting movement in that each lowerroll support 5 of the support segments 2 is movable about the pivot axis13 of the fixed bearing 11 in a direction 14 roughly perpendicular withrespect to the longitudinal extension 8 of the strand guide 1 and in aplane that passes through the longitudinal extension 8 of the strandguide 1 in vertical direction. This movability can be realized either bymeans of threaded spindles or through hydraulic adjusting cylinders 15acting e.g. directly on the lower roll support 5 or on a wedge that isslideably guided in the movable bearing 12. Vertically adjustable shimsmay serve for adjusting and securing the position of a support segment.To ensure a precise extent of the adjusting movement, a position sensor16 is preferably integrated in the movable bearing 12. The actual valueof the position of the support segment 2 detected by the position sensor16 is passed on to a comparator 17 of a controller 18, is there comparedwith the setpoint, and the hydraulic adjusting cylinder 15 is actuatedvia a valve 19 as a function of this comparison.

To enable the strand guide 1 to be readjusted after coarsely mountingthe support segments 1 on the longitudinal carriers 3, i.e. to avoidjumps between the successively arranged support segments 2—these woulddeform the strand which still has a thin strand shell in an unacceptablemanner and could cause a breakthrough of the strand—the followingprocedure is employed:

First of all, a casting gap gauge, by which both the casting gap and itslocal curvature can be measured, is moved through the strand guide 1 inorder to detect the actual position of the support rollers 4 and thesupport segments 2. The arrangement of the supporting rollers 4 withineach support segment 2 can be accurately adjusted with great precisionin a machine shop, such that mis-positioning need not be anticipated inthis respect. After carrying out the measurements with the casting gapgauge (such a device is described e.g. in AT-B - 393.739), the measuringreport is evaluated and the necessary corrective movements of theindividual support segments 2 that are still to be carried out arecalculated. This can be done with the aid of a computer.

If e.g. a position of three support segments 2, 2′, 2″ arranged onebehind the other is known from the measuring report, as is shown in FIG.2—although for reasons of simplicity only for the lower roll support5—it can be seen that the middle support segment 2′ deviates from theideal path of the strand guide, which is illustrated by a dashed anddotted line 20. According to the example, it is located about 1 mm toolow. In this example, a roll diameter of 300 mm and a roller pitch of330 mm are realized. According to the invention, correction of theposition of the support segments 2, 2′, 2″ is carried out in that thesecond support segment 2′ on the end on which it has the movable bearing12 is lifted to such an extent that a minimal curvature of the strandguide 1 results between the neighboring supporting rollers 4 of theneighboring support segments 2, 2′. In the same manner, the thirdsupport segment 2″ is lowered at the site where it is fastened to thelongitudinal carriers 3 by means of a movable bearing 12, likewise untilthe local curvature between the neighboring supporting rollers 4 of theneighboring support segments 2 and 2′ is a minimum.

To calculate the curvature, a tangent circle is laid to three successivesupporting rollers 4 of which one belongs to the one and two belong tothe other neighboring support segment 2, and the radius and curvature ofthis circle are calculated. In FIG. 4, the local curvature above therespective middle supporting roller of the three selected supportingrollers 4 of neighboring support segments 2, 2′, 2″ has beenillustrated. A solid black square has been used to indicate the valuesresulting in the case of imprecise mounting of the segments as describedabove. An empty square has been used to illustrate the curvature valuesafter correction. In the example, the maximal curvature is thus reducedto about a third of the original value as a result of the correction.The curvature in conjunction with the shell thickness of the strand canbe interpreted as a measure of the expansions occurring in the two-phaselayer (between the solidified shell of the strand and the liquid core)and hence as a criterion of quality.

According to the embodiment of a movable bearing 12 represented in FIG.6, a tension rod 21 is wedged to the supporting framework 3, i.e. at alongitudinal carrier, and is connected with the lower roll support 5.The roll support 5 is displaceable along the tension rod 21, so that thesupport segment 2 is pivotable about the fixed bearing 11. A hydraulicadjusting cylinder 15 serves for realizing a movement of the rollsupport 5 relative to the supporting framework 3.

The cylinder 22 of the hydraulic adjusting cylinder 15 is supported onan additional carrier 23 likewise wedged with respect to the tension rod21, so that the additional carrier 23 is fixed in its position relativeto the supporting framework 3. For equal and radially symmetrical forceintroduction, the piston 24 of the hydraulic adjusting cylinder 15 ispreferably constructed as a tubular piston passed through by the tensionrod 21. The front end 25 of the piston 24 is supported on the rollsupport 5.

Between the additional carrier 23 and the roll support 5 a balancingcylinder 26 is provided which is arranged in parallel to the hydraulicadjusting cylinder 15 and is at all times actuated in such a way thatthe roll support 5 rests against the front end 25 of the piston 24 ofthe hydraulic adjusting cylinder 15, i.e. is pressed against the same.The cylinder of the balancing cylinder 26 is connected with theadditional carrier 23, and the piston with the roll support 5. Thisbalancing cylinder could also be arranged between the additional carrier23 and the roll support 5 in a position rotated through 180°. Thebalancing cylinder 26 enables the roll support 5 to be positionedwithout play in relation to the supporting framework 3 and in additionserves e.g. as a position sensor for detecting the actual position ofthe roll support 5, as is shown schematically in FIG. 5. In this manner,crushing or contamination of the site of application of the force of thehydraulic adjusting cylinder 15 on the roll support 5—hence on thebearing site of the piston 24—exert no negative influence on theset-point to which the support segment 2 is to be adjusted.

As can be seen particularly from FIG. 5, hydraulic working ducts 27, 28can each be connected with a respective chamber 32, 33 of the hydraulicadjusting cylinder 15 via throttles 29 or screens and directionalcontrol valves 30A, 30B and controlled nonreturn valves 31A, 31Bprovided downstream of the same. The respective position of the piston24 of the hydraulic adjusting cylinder 15—and hence of the supportsegment 2—is detected via the position sensor, i.e. the balancingcylinder 26, and its signal is then passed on to a comparator 34 of athree-level controller 35. The set-point setting for the position of thepiston 24 of the hydraulic adjusting cylinder 15 can be fed into thecomparator 34. If the actual value deviates from the set-point, thethree-level controller 35 becomes active, with the valve 30A switchingat the signal +1 and the valve 30B at the signal −1.

The nonreturn valves 31A and 31B located in the hydraulic working ducts27, 28 leading to the two chambers 32 and 33 of the hydraulic adjustingcylinder 15 are each acted upon via the control ducts 36 by thehydraulic working duct 27, 28 leading into the respective other chamber.

According to the embodiment illustrated in FIG. 6, the balancingcylinder 26 is adapted to be pressurized by a separate hydraulic workingduct 37. Further, there is provided a pressure control valve 38,limiting the force of the piston 24 of the hydraulic adjusting cylinder15.

In FIG. 7, the control of the three-level controller 35 is explained inmore detail, with the selection of the directional control valves beingplotted on the ordinate and the deviation on the abscissa. If thethree-level controller 35 gives the signal +1, the magnet of thedirectional control valve 30A is switched, whereas the magnet of thedirectional control valve 30B is without current. If the signal of thethree-level controller 35 is 0, both magnets of the directional controlvalves 30A and 30B are without current; at the signal −1, the magnet ofthe directional control valve 30A is without current and the magnet ofthe directional control valve 30B switches.

FIG. 9 shows a slightly modified circuitry comprising a 4/3-portdirectional control valve 30C and provided with a current control valve39 with rectification. FIG. 10 shows a similar circuitry likewisecomprising a 4/3-port directional control valve 30C, yet without acurrent control valve. According to this embodiment, throttles 29 orscreens are arranged in the hydraulic working ducts 27, 28 between thenonreturn valves 31A, 31B and the hydraulic adjusting cylinder 15, inaddition to throttles 29 or screens provided in front of the 4/3-portdirectional control valve 30C. In this way, a great possibility ofvariation with respect to the speed of the hydraulic adjusting cylinders15 can be achieved. The throttles or screens can be dimensioned thelarger the more there are provided of them, which has the advantage thatthe throttles 29 or screens are considerably less sensitive tocontamination.

By omitting the throttles 29 or screens provided before the 4/3-portdirectional control valve 30C in the embodiment illustrated in FIG. 6 ordimensioning them larger than the throttles 29 or screens arrangedimmediately in front of the hydraulic adjusting cylinder 15, the mainthrottling effect (or main screening effect) can be achieved between thenonreturn valves 31A and 31B and the hydraulic adjusting cylinder 12,whereby the switching times of the nonreturn valves 31A and 31B may bekept particularly short. In addition, oscillations of the nonreturnvalves 31A and 31B are avoided by this measure. Basically, thearrangement of throttles 29 or screens in the immediate vicinity of thehydraulic adjusting cylinder 15, i.e. between the nonreturn valves 31Aand 31B and the hydraulic adjusting cylinder 15 can also be realized inall of the other embodiments shown in FIGS. 1, 2, 5 and 7, such that theadvantages that have been described above will also result with theseembodiments.

In FIG. 11 there is illustrated a valve-throttle combination forrealizing two adjusting velocities of the hydraulic adjusting cylinder15. The piston 24 of the hydraulic adjusting cylinder 15 can be moved atrapid speed or at creep speed. In this circuitry in which the partsurrounded by dashed and dotted lines is identical with the circuitryaccording to FIG. 5, throttles 40 or screens, each of which can bebridged by a bypass 41, 42, are additionally connected preceding thedirectional control valves 30A and 30B in the hydraulic working ducts27, 28. Bridging can be achieved by means of a directional control valve43 which is provided in the bypass ducts 41, 42 and which can beactivated or deactivated via a five-level controller. The five-levelcontrol is realized by means of a three-level controller 35 according toFIG. 5 having a mode of operation in accordance with FIG. 7 and a rapidspeed/creep speed switch 44 whose mode of operation is explained in FIG.8. As the piston 24 of the hydraulic adjusting cylinder 15 approachesthe switching zone of the three-level controller 35, a lower speed isswitched via the rapid speed/creep speed switch 44, namely by means ofone of the interconnectable screens 40, so that a more accuratepositioning can be achieved. By the signal +1, the rapid speed/creepspeed switch 44 moves the directional control valve 43 into the positionfor the creep speed, which is shown in FIG. 8, and by the signal 0 itmoves the directional control valve 43 into the rapid speed position inwhich the hydraulic medium flows via the by-pass ducts 41 and 42.

Instead of the three-level controller 35 it is also possible to providea controller with a pulse-width output.

What is claimed is:
 1. Strand guide (1) for a continuous casting plant,comprising a plurality of strand supporting elements (4) for supportingthe strand, several support segments being fastened adjacent each otheron a supporting framework (3) designed in one piece in its longitudinalextension, wherein each support segment (2) is fastened to thesupporting framework (3) by means of a fixed bearing (11) and movablebearing (12) spaced apart therefrom in the longitudinal extension of thestrand guide and each support segment (2) by at least one bearing ispivotally mounted to the supporting framework (3) so as to be pivotableabout an axis (13), said axis being oriented transversely with respectto the longitudinal extension (8) of the strand guide (1) andhorizontally, as well as in a vertical plane passing through thelongitudinal extension (8) of the supporting framework (3) to at leastone bearing (11, 12)) is mounted so as to be adjustable with respect tothe supporting framework (3) in a direction roughly perpendicular to thelongitudinal extension (8) of the supporting framework (3) to enable thepivoting movement of the support segment (2), characterized in that ameasuring device for detecting the pivoting movement of the supportsegment (2) is provided which via a controller (18) is coupled with anadjusting device (15) for adjusting the position of the support segment(2).
 2. Strand guide according to claim 1, wherein vertically adjustableshims are provided for adjusting the position of the support segments(2).
 3. Strand guide according to claim 1, characterized in that athreaded spindle is provided for adjusting the adjustable bearing (12).4. Strand guide according to claim 1, characterized in that foradjusting the adjustable bearing (12) an axially displaceable wedge isprovided which is movable by means of a hydraulic adjusting cylinder. 5.Strand guide according to claim 1, characterized in that for adjustingthe adjustable bearing (12) there is provided a hydraulic adjustingcylinder (15) which acts between the supporting framework (3) and thesupport segment (2).
 6. Strand guide according to claim 1, wherein, asmeans for actuating the hydraulic adjusting cylinder, at least onedirectional control valve is provided which is capable of being switchedvia a controller having at least three levels to which the actual valuedetected by the position sensor can be fed via a coupling.
 7. Adjustingdevice according to claim 6, characterized in that a throttle (29) orscreen is integrated in at least one hydraulic working duct (27, 28) ofthe hydraulic adjusting cylinder (15) leading from a pressure-mediumsupply station to the directional control valve (30A, 30B, 30C) and fromthis latter to the hydraulic adjusting cylinder (15).
 8. Adjustingdevice according to claim 6, characterized in that a current controlvalve (39) with rectification is integrated in at least one hydraulicworking duct (27, 28) leading from a pressure-medium supply station tothe directional control valve (30A, 30B, 30C) and this latter to thehydraulic adjusting cylinder (15).
 9. Strand guide according to claim 6,wherein in the hydraulic working duct (27, 28) leading to the hydraulicadjusting cylinder (15) there is provided a throttle (29) connectedimmediately upstream of the hydraulic adjusting cylinder (15). 10.Strand guide according to claim 6, wherein an additional directionalcontrol valve (43) is provided connected in parallel with a throttlewith rectification.
 11. Strand guide according to claim 10, wherein acontroller (35, 44) having at least five levels is provided as acontroller.
 12. Strand guide according to claim 6, characterized in thatthe position sensor (26) is formed by a balancing cylinder (26)connected in parallel with the hydraulic adjusting cylinder (15) andacting diametrically opposed to the hydraulic adjusting cylinder (15)and which on the one hand is connected with the supporting framework (3)and on the other hand with a support segment.
 13. A strand guideaccording to claim 1, wherein said strand supporting elements (4) aresupport segments (2) carrying supporting rollers (4).
 14. A strand guideaccording to claim 1, wherein said measuring device for detecting thepivoting move of the supporting segment (2) is a position sensor.
 15. Astrand guide according to claim 1, wherein said measuring device fordetecting the pivoting movement of the support segment (2) is an anglemeasuring device.
 16. A strand guide according to claim 1, wherein, asmeans for actuating the hydraulic adjusting cylinder, at least onedirectional control valve is provided which is capable of being switchedvia a controller with a pulse-width output to which the actual valvedetected by the position sensor can be fed via a coupling.
 17. A strandguide according to claim 6, wherein in the hydraulic working duct (27,28) leading away from the hydraulic adjusting cylinder (15) there isprovided a screen connected downstream of the hydraulic adjustingcylinder (15).
 18. A strand guide according to claim 6, wherein anadditional directional control valve (43) is provided connected inparallel with a sensor with rectification.
 19. A strand guide accordingto claim 6, wherein an additional direction control valve (42) isprovided connected in parallel with said current control valve withrectification.
 20. Strand guide according to claim 1, wherein saidsupporting framework is arcuate.
 21. Method of adjusting the position ofsupport segments (2) fastened successively in a supporting framework (3)and provided with strand supporting elements (4) with each supportsegment (2) being fastened to the supporting framework (3) by means of afixed bearing (11) and a movable bearing (12) spaced apart therefrom inthe longitudinal extension (8) of the strand guide (1), said methodbeing by detecting and controlling the pivoting movement of the supportsegment, and comprising the step of pivoting, about its fixed bearing(11), the support segment adjoining the support segment of neighboringsupport segments (2) whose strand supporting elements (4) result in apath of the strand guide exhibiting a jump at the junction point of thesupport segments (2), until a tangent circle laid to three neighboringstrand supporting elements (4) of which one strand supporting element(4) belongs to one support segment and two supporting elements (4) tothe neighboring support segment (2) exhibits a radius or a curvaturewhose deviation from the desired (ideal) radius or from the associatedcurvature becomes a minimum.